As the density of semiconductor devices become higher and line widths thereof become finer, the wavelengths of lights used for exposure devices and mask inspection devices also become shorter every year, and an exposure device and mask inspection device having a light source with a 193 nm wavelength light are at the stage of practical use. For example, a solid-state laser (laser light source device) which generates light with a 193 nm wavelength is constructed such that the light of a semiconductor laser with a 1547 nm wavelength is used as a fundamental wave, and is branched into a plurality of laser lights by an optical branching means, and a plurality of these laser lights are amplified in parallel by a fiber amplifier, and the emitting ends (fibers) thereof are bundled and entered into a wavelength conversion optical system, and by this wavelength conversion optical system, the wavelength of the fundamental wave is converted into eighth-harmonic waves, and a 193 nm of high power light is acquired (for example, Japanese Patent Application Laid-Open No. 2000-200747 (pages 18 to 25, see FIG. 11). Therefore when such a laser beam is used for an exposure device and mask inspection device, it is very important to improve conversion efficiency in wavelength conversion, including the wavelength conversion optical system.
However, with the above method in which fibers are spatially bundled, it is difficult to condense all light to one point on the wavelength conversion crystal for wavelength conversion, and to satisfy the acceptance angle of this wavelength conversion crystal, therefore high conversion efficiency cannot be implemented. It is possible to construct to form an image on the wavelength conversion optical system for each of the bundled fibers using a micro-lens array, but it is difficult to implement the necessary processing and adjustment accuracy to acquire high conversion efficiency.